Our present invention relates to an apparatus for wrapping a stacked-goods unit with a shrink-foil wrap having a frame forming a portal, a conveyor extending through the portal for the stacked-goods units, drivable shrink-foil rolls whose foil webs are connected together at their ends and form in the portal a shrink-foil curtain, and double-weld beams arranged on both sides of the portal and movable toward one another.
In the usual shrink wrapping apparatus, the stacked-goods unit is displaced via the conveyor, which can be a roller conveyor or a chain conveyor or can be comprised of traverses, into the shrink-foil curtain. By feeding the stacked-goods unit into the shrink-foil curtain, the stacked-goods unit is wrapped on three sides with foil. Thereafter, the double-weld beams are displaced along the right and left sides perpendicularly to the conveyor and guide the shrink foil curtain onto the rear fourth side of the stacked-goods unit and meet in the middle of the latter. There the shrink-foil curtain is provided with a double-weld seam which is separated by a heated wire in the middle of the double-weld seam so that ahead of the following stacked-goods unit a further shrink-foil curtain is formed. The double-weld beam can be provided with a weld seam cooling for high cycling rates of the apparatus.
In addition, clamping devices can be provided on the double-weld beams which serve to prevent the weld seam from being strained during the welding and cooling phases by the stretched shrink-foil curtain.
The known apparatuses for the described purposes have shrink-foil roll axes which extend vertically. Since the shrink-foil rolls as a rule are oriented horizontally when they are brought to the apparatus by a fork-lift vehicle or a manually operated lift truck, they must be tilted through 90xc2x0 before they can be set in place in the apparatus.
This means a significant expense and is not without dangers. In addition, the drives for the shrink-foil rolls engage at their axes. As a consequence, the speeds of the drives must be matched to the decreasing circumference of the shrink-foil rolls by expensive electronic controls.
It is an object of the invention to simplify the replacement of shrink-foil rolls.
Another object of this invention is to provide a shrink-foil wrapping apparatus which is free from the drawbacks of earlier systems as described above.
It is another object of this invention to provide a shrink-wrapping apparatus which can be more rapidly loaded with the rolls of shrink-foil wrap and is nevertheless compact, easily maintained and easily operated.
A further object of this invention is to provide a shrink-foil wrapping apparatus which is more versatile than earlier apparatus, can accommodate stacked or palletized units of different heights and can wrap the units with webs of different widths.
These objects and others which will become apparent hereinafter are attained, in accordance with the invention, in an apparatus for the shrink wrapping of stacked or palletized goods units which comprises:
a wrapping station formed with a portal;
a conveyor extending through the portal for carrying a succession of stacked-goods units to be wrapped through the portal;
mounting means at each side of the portal for holding a respective roll of a shrink-foil wrap in a horizontal orientation and journaling the respective roll on a respective horizontal axis;
means for driving each of the rolls about the respective axis;
rerouting means at each side of the portal for drawing a respective web of shrink-foil wrap from each roll and orienting the respective web in a vertical plane; and
a pair of double-weld beams engaging the webs from each of the rerouting means and welding the webs together to form a shrink-wrap curtain across the portal ahead of a stacked-goods unit displaced along the conveyor, the double-weld beams drawing the webs together behind the stacked-goods unit to form a seam and produce another curtain ahead of a successive stacked-goods unit.
It is important to the invention, as will be described in greater detail below, that the rolls of the foil wrap are mounted horizontally and preferably parallel to the conveyor and perpendicular to the plane of the portal so that the rolls can be loaded into the respective mounting means from the respective sides of the apparatus utilizing conventional fork-lift trucks and the like. The rerouting means can include at least one roller which is inclined to the horizontal and to the vertical and, if desired, a plurality of other rollers around which the web can be looped, including at least one dancer roller per rerouting means.
In the invention, therefore, the axes of the shrink-foil rolls extend horizontally and rerouting devices are provided for the foil webs which are paid off from the shrink-foil rolls to the shrink-foil curtain. Upon replacement of the shrink-foil rolls, a shrink-foil roll can be supplied with the aid of a fork lift or manual-lift truck so that, like they would be supplied on a pallet, they can be laid in the apparatus. This reduces the handling cost and the danger of accidents in replacement of the shrink-foil rolls.
It is advantageous in this regard for journals for the axes of the shrink-foil rolls to be arranged on the outer sides of the frame.
According to the invention, at least a further pair of drivable shrink-foil rolls can be provided whose foil webs can be connected with one another at their ends and form a further shrink-foil curtain in the portal. The axes of these further shrink-foil rolls extend horizontally and rerouting devices are provided for the foil webs running from these shrink-foil rolls to the shrink-foil curtain. The respective rerouting devices of at least one pair of drivable shrink-foil rolls are arranged for upward movement of the foil webs and the further shrink-foil curtain can be height-adjustable or at least a further pair of drivable shrink-foil rolls is provided whose foil webs can be connected together at their ends and form in a portal a further shrink-foil curtain.
The rerouting devices can be arranged for upward swinging of the foil webs and the further shrink-foil curtain about an axis arranged orthogonally to the fastening axes of the rerouting devices.
There is also the possibility of arranging on at least one side of the frame, a multiplicity of shrink-foil rolls, one above the other. Then one of the shrink-foil rolls can serve as a supply roll which is brought into operation when another of the shrink-foil rolls is consumed.
As a result, the downtime in foil replacement is reduced. One can, however, also provide shrink-foil rolls of different foil widths which can be utilized as need dictates.
To reduce the spatial requirements, the shrink-foil rolls can be arranged to be one sided. In this case, the foil web for the one side of the shrink-foil curtain is displaced over the apparatus or under it.
The foil webs can, in addition, be appropriately guided or swung so that they form a shrink-foil curtain with a height which is greater by, for example, 1.5 times, thereby enabling the wrapping of stacked-goods units whose heights are greater than the height of an individual foil web.
In a preferred embodiment of the invention, each shrink-foil roll is juxtaposed with a friction wheel drive engaging at its circumference, and a foil storage is provided for the foil web on its path to the shrink-foil curtain.
This allows electronic control of the speed of the drive to match the decreasing circumference of the shrink-foil roll resulting from foil consumption. The speed of the drive is also no longer dependent upon the cycling rate of the apparatus or the transport speed of the stacked-goods units since the foil storage can be filled continuously and imparted as need arises. The foil storage is sufficient if it includes at least one dancer roller.